There is need to disinfect surfaces and materials within buildings and other enclosures, such as locker rooms, clubhouses, gymnasiums, equipment related to athletic activities, health care facilities, and vehicles for transportation for land, sea, and air. It is known to use steam for disinfecting surfaces. Portable steam generators are commercially available which typically work with a “wand” that allows manual application of steam directly to surfaces of floors, walls, ceilings, fixtures, furniture, equipment, and the like. Such application of steam sterilizes these surfaces but does not provide an on-going antimicrobial protection of these surfaces.
Chitosan possesses good antibacterial properties against various bacteria and fungi because of its polycationic nature. Chitosan is obtained from the shells of crabs, shrimps and other crustaceans. It is a non-toxic, biodegradable and biocompatible natural polymer, and has long been used as a biopolymer and natural material in pharmaceutical, medical, papermaking and food processing industries. Chitosan is a basic polysaccharide obtained by deacetylation of the chitin which is present in the carapace of these crustaceans. However, because of strong hydrogen bonds, chitosan itself is hardly soluble in a solvent other than an acidic aqueous solution and, even if it is made into an aqueous solution, the viscosity of the solution can become high whereby its handling is difficult. In addition, Chitosan has strong water-absorption ability due to the presence of many hydrophilic polar groups. In order to overcome these problems chitosan has been incorporated into polymeric core-shell particles dispersed in water (see U.S. Pat. No. 8,226,962). This methodology is relatively complex and appears useful only for textiles and not for all surfaces.
What is needed is an aqueous solution of chitosan or related substances that overcomes the problems of viscosity, high acidity, and water absorption and which will provide sustained antimicrobial protection to all surfaces by a simple method of application.